X-ray diffuse scattering of p-type porous silicon

An x-ray diffuse scattering investigation of p-type porous silicon (PS) is reported. Synchrotron radiation and laboratory measurements of the x-ray diffuse scattering at small and large scattering wave-vector q values are presented. At small q values and for p(-)-type material, small isotropic crystallites of a few nanometers diameter are shown, whereas for p(+)-type material the main cylindrical crystallites are larger. At large q values the fine p(+) PS structure is investigated and reveals the presence of small spherical crystallites around the main cylindrical crystallites. The elastic relaxation of silicon crystallites in the porous structure is also presented for oxidized and for as-formed samples, using reciprocal space maps. PS superlattice diffuse scattering is then observed. Finally, these results are discussed in relation to previous x-ray studies and other methods of structural observation. (C) 2002 American Institute of Physics.